The present invention relates generally to the field of wood processing. More particularly, the present invention relates to a method and apparatus for reducing oversized wood chips.
Wood processing mills generate wood scraps of various sizes during the wood cutting process. In plywood processing mills, the wood scraps can be in the form of thin, elongate, veneer-like strips that can be generally in the range of six inches to twenty-four inches long, two to six inches wide, and one eighteenth of an inch thick. It should be understood that such dimensions are provided for example only and should not be construed as limiting the present invention. Likewise, any dimensions discussed herein are for example purposes only and should not be construed as a limitation on the present invention. To be useful in the manufacture of paper, cardboard, and other recyclable materials, wood scraps must be reduced into wood chips of an acceptable size and shape.
Mills use screens to separate acceptable wood chips from oversized wood chips. The oversized wood chips are sometimes referred to as xe2x80x9coversxe2x80x9d because they pass over the separating screens.
There is a need for a machine to reduce the overs to an acceptable size. More specifically, the overs need to be reduced to wood chips that are relatively uniform in size, having gross dimensions of one inch or less, without crushing the overs into unusable bits. It should be understood that the desired chip dimension of one inch is provided as an example only and should not be construed as limiting the present invention. Many different machines have been tried, such as disc chippers, hogs, drum chippers, and the like, with very little success in producing usable chips. Overs are generally long, thin, and lightweight. The known machines use a high-impact method which tends to crush the overs into finer slivers and particles that are unacceptable for later use in making paper and cardboard.
The need to reduce overs to an acceptable and useful size without destroying them is a problem which has existed since the beginning of saw mills, veneer mills, and other wood working facilities.
The above and other needs are met by the present invention which, in one embodiment, provides an apparatus and a method for reducing certain oversized wood chips known as xe2x80x9coversxe2x80x9d by cutting them smoothly, with relatively no impact, such that the resulting chips can be used to make paper, cardboard, and other recyclable materials.
Generally described, the present invention in one embodiment comprises a table saw with an array of spaced-apart circular saw blades and a reciprocating plunger to sweep the overs through the saw blades. The face of the plunger is shaped to align the overs in the optimum orientation for cutting and is also shaped to hold the overs in place during cutting.
In one aspect of the invention, the apparatus includes a frame, a saw assembly including an array of blades, a moveable plunger, and a plunger actuator. The face of the plunger contains an array of recesses located and sized to accept insertion of the array of saw blades. The plunger moves from a first position to a second position. In the first position, the plunger is disengaged from the array of blades. In the second position, the plunger is engaged with the array of blades such that the blades are at least partially inserted in the recesses in the face of the plunger. As the plunger moves from the first position to the second position, the plunger sweeps the wood chips into the array of saw blades and beyond their cutting edges.
In one preferred embodiment, the saw assembly includes an array of circular saw blades mounted on a common shaft releasably coupled to a saw motor. The overs are swept into the gaps between the circular saw blades which are maintained by spacers. For easy removal and replacement, the entire shaft may be uncoupled from the saw motor and lifted out of the assembly.
In another aspect of the invention, the frame of the apparatus includes a channel having a floor, side walls, and a plurality of floor slots through which the array of saw blades protrudes. The plunger is configured to move back and forth within the channel as it sweeps the wood chips into the array of saw blades.
In one preferred embodiment of the invention, the plunger face includes a planar portion and an overhanging portion. The planar portion aligns the overs parallel to the plunger face for cutting as the plunger moves toward the blades. The overhanging portion is shaped to hold the overs in place during cutting by resisting the turning force of the saw blades. The apparatus further includes a chip dam located above the plunger to align the overs parallel to the plunger face as the plunger retracts away from the blades.
In one preferred embodiment, the plunger actuator includes a motor and a drive assembly to move the plunger. The drive assembly may include sensors and a controller in communication with the sensors to monitor the plunger position and control its movement. The drive assembly may consist of a pair of cables mounted on a cable spool connected to a motor. The pair of cables may be attached to the keel of the plunger and supported by an idler pulley to convert the rotational movement of the spool into translational movement of the plunger.
In one alternative embodiment, the apparatus includes a frame, an an array of circular blades driven by a motor, a feeder assembly, and an actuator for rotating the feeder assembly. The feeder assembly includes a number of paddles attached to a central hub. The feeder assembly is mounted on the frame near the saws to permit the intersection of the paddles and the saw blades. The paddles include an array of slots that match the saw blades. In one preferred arrangement of this embodiment, the paddles include a flat portion near the hub and a contoured outer portion near the ends of each paddle. The contoured portion of each paddle is sized to capture an incoming flow of wood chips, shaped to align the wood chips parallel to the axis of rotation of the hub, and positioned to guide the wood chips into and completely through the saw blades.
In another aspect of the invention, the method comprises the steps of providing a moveable plunger and a saw assembly for the cutting the overs, and moving the plunger from a first position to a second position, as described above. The step of moving the plunger sweeps the wood chips into the array of saw blades and beyond their cutting edges.
In one preferred embodiment, the method of the present invention includes the preliminary steps of attaching a blank plunger face, without recesses, to the moveable plunger when it is disengaged from the saws. By moving the blank plunger face slowly into the saws, the array of saw blades cut a matching array of recesses into the plunger face. This preliminary method step assures a matching fit between the saw blades and the recesses.
In one preferred embodiment, another aspect of the method includes the step of aligning the wood chips to be roughly parallel to the plunger face before cutting. This step may be performed by a planar portion of the plunger face as the plunger moves toward the saw blades. In another aspect, the method may include the step of containing the wood chips during cutting by using an overhanging portion of the plunger face. In another aspect, as the plunger moves away from the saw blades, a chip dam mounted above the plunger may perform the step of aligning the wood chips to be roughly parallel to the plunger face.
Therefore, it is an object of the present invention to provide an improved wood processing apparatus.
It is a further object of the present invention to provide an improved wood processing method.
It is a further object of the present invention to provide an improved method of processing wood chips which is efficient in operation.
It is a further object of the present invention to provide an improved method of processing wood chips which is simple in operation.
It is a further object of the present invention to provide an improved method of processing wood chips which is effective in providing proper chip size.
It is a further object of the present invention to provide an improved apparatus of processing wood chips which is efficient in operation.
It is a further object of the present invention to provide an improved apparatus of processing wood chips which is simple in operation.
It is a further object of the present invention to provide an improved apparatus of processing wood chips which is effective in providing proper chip size.
These and other objects, features, and advantages of the present invention will become apparent upon reading the following detailed description of a preferred embodiment of the invention when taken in conjunction with the drawing and the appended claims.